a) Field of the Invention
The invention is directed to a vacuum valve comprising a valve body with a valve opening having a longitudinal axis and a valve seat surrounding the valve opening, a valve plate which is adjustable from an open position, in which it releases the valve opening, to an intermediate position, in which it covers the valve opening but is lifted from the valve seat, into a closed position in which it contacts the valve seat, and from the closed position to the intermediate position into the open position, a valve rod carrying the valve plate, a transverse drive unit by means of which the valve plate can be displaced in a transverse adjusting direction extending transverse to the longitudinal axis of the valve opening from its open position into its intermediate position and opposite the transverse adjusting direction from its intermediate position into its open position, and a longitudinal drive unit by means of which the valve plate can be displaced in a longitudinal adjusting direction extending parallel to the longitudinal axis of the valve opening from its intermediate position into its closed position and opposite the longitudinal adjusting direction from its closed position into its intermediate position.
b) Description of the Related Art
A valve of the kind mentioned above is known from US 2004/0079915 A1, for example. A carrying body is arranged at the valve rod that is displaceable in axial direction by the transverse drive unit, and the longitudinal drive unit for pressing the valve plate against the valve seat is arranged at the carrying body. In one embodiment form, a supporting plate is held at the carrying body on the opposite side of the valve plate and can be pressed against the inner wall of the valve body by piston-cylinder units in order to absorb the reaction force of the valve plate. This construction is relatively complicated, and therefore costly, and results in a relatively large construction. In another embodiment form, the contact pressing plate can also be dispensed with and the reaction force of the valve plate must be absorbed by the valve rod or the valve rod must be correspondingly flexible so that the carrying body can be pressed against the inner wall of the valve body, which inner wall is located opposite from the valve seat.
Another valve of the type mentioned above is known from U.S. Pat. No. 6,561,484 B2. Either a carrying plate having a piston-cylinder unit, by means of which the valve plate is pressed against the valve body, is arranged at the valve rod, or the valve plate having a piston-cylinder unit by means of which a supporting plate is pressed against an inner wall of the valve body opposite from the valve seat is arranged at the valve rod. The valve plate is displaced relative to the valve seat. A similar vacuum valve is also known from U.S. Pat. No. 6,561,483 B2.
Other vacuum valves in which the valve plate is displaceable by piston-cylinder units relative to a carrying body arranged at the valve rod are known from U.S. Pat. Nos. 6,056,266 and 6,899,316 B2.
In the vacuum valve shown in U.S. Pat. No. 6,431,518 B1, the valve plate is arranged at a valve rod which is likewise adjustable by a piston-cylinder unit between a position in which the valve opening is released and a position in which the valve opening is covered but in which the valve plate is lifted from the valve seat. The cylinder of this piston-cylinder unit is swivelable around an axis oriented at right angles to the longitudinal axis of the valve rod and at right angles to the longitudinal axis of the valve opening. By swiveling this cylinder by means of another drive unit which can be constructed, for example, as a piston-cylinder unit, the valve plate is pressed against the valve seat.
U.S. Pat. No. 6,776,394 B2 shows a pendulum valve in which the valve plate is pressed against the valve seat in the closed position of the valve plate by means of tappets actuated by pistons which are mounted so as to be displaceable in cylindrical bore holes of the valve body.